dissection

1. The act or an instance of dissecting.
2. Something that has been dissected, such as a tissue specimen under study.
3. A detailed examination or analysis.

Dissection of the human body is the act or art of cutting open the body in order to display and study the topographical anatomy and structure of its parts. It has its origins in antiquity. The evolution of the practice of dissection is a curious history of heroic academic endeavour, ingenuity, artistic idealism, romance, and iniquity. Claude Bernard, the French physiologist, rightly described anatomy as the basis of all physiology. Without a proper understanding of both there could never have been a scientific approach to the study and practice of medicine.

The story of the systematic dissection (anatomizing) of human corpses really begins in Alexandria (c.300-250 bc). It was here that anatomy first became a recognized discipline and that a proper systematized description of the structure of the human body was made. This was largely due to the work of Herophilus and Erasistratus. Herophilus is universally acknowledged as the ‘father of anatomy’ and is believed to be the first person to have performed a public dissection of the human body. He is thought to have performed approximately 600 dissections during his career, and it is alleged that some of these were vivisections (dissections of live persons) of condemned criminals. His contemporary, Erasistratus, also performed dissections. Together they made significant contributions to the study of abdominal and pelvic viscera, vascular anatomy, and neuroanatomy. Following the decline of Alexandrian science, the seat of serious anatomical study shifted to Rome. Here, Galen of Pergamum (129-216 ad) was the pre-eminent anatomist. Galen based his anatomical observations solely on animal dissections, and made the serious misjudgement of inferring that human anatomical features were identical to those in animals. Galen's authoritarian teaching held powerful sway throughout his lifetime and for a considerable period thereafter, resulting in the propagation of many erroneous concepts. For over a thousand years following Galen's death, there was a virtual cessation of any form of original anatomical inquiry. The practice of dissection had stopped altogether, chiefly due to contemporaneous religious proscriptions. This period of general intellectual stagnation is termed the Dark Ages. The resumption of the exploration of human anatomy by dissection, and the scientific impulse to verify or challenge Galenic doctrine, were part of the general intellectual reawakening (the Renaissance) that commenced in Italy during the thirteenth and fourteenth centuries and spread rapidly through the rest of Europe. The proliferation of this intellectual activity owed much to the many universities which were established in Italy and elsewhere in Europe, notably those in Salerno, Bologna, Padua, Florence, Louvain, Paris, and Montpelier. There is evidence that human post-mortem examinations were conducted in Bologna towards the end of the thirteenth century. These, however, were done not primarily for anatomical study, but to ascertain the cause of death. The first comprehensive human dissection to be done in post-Alexandrian times was performed in Bologna, in 1315 ad, by Mondino de Luzzi, a professor of medicine at the university in Bologna. In the following year he published his treatise, Anathomia, which reads remarkably like a practical dissection manual. Mondino's dissections were public events. He performed these in person and was largely responsible for restoring to anatomy its original respectability and status as a recognized discipline. None of Mondino's successors in Bologna made any significant contribution to anatomical knowledge.

The next milestone in the history of dissection occurred in 1543, when Andreas Vesalius, a young professor of anatomy in Padua, published his masterpiece De Humani Corporis Fabrica Libris Septem (‘the seven books on the fabric of the human body’). This was an exhaustive and systematically classified compendium of anatomical observations, sumptuously illustrated with accurate depictions of dissections based on Vesalius' vast personal experience, and laying to rest all Galenic misconceptions. Vesalius was largely responsible for inspiring the modern scientific study of topographical anatomy based upon direct observation at dissection, as opposed to the traditional ecclesiastical method of interpreting the written word. Realdus Columbus, Gabriel Fallopius, and Heironymus Fabricius continued the Vesalian anatomical tradition in Padua. Between the thirteenth and seventeenth centuries, Bologna and Padua (principally the latter) were the leading centres of anatomical study in the world.

It is generally acknowledged that Joannes Caius, a colleague of Vesalius, was the first to popularize the study of practical anatomy by dissection in England. Caius taught anatomy in Cambridge. However, neither Caius nor any of his immediate successors made any original contributions, and anatomical study in England was generally barren until the advent of William Harvey. Harvey's great intellectual triumph, De moto cordis et sanguinis, was published in 1628, and proved conclusively the circulation of blood. He reached his findings ‘by reason and experiment’ based on observations made in the course of dissecting several bodies, including those of his own father and sister (post-mortem) — a most unusual manifestation of clinical detachment.

During the fifteenth century, in the wake of the revival of anatomical dissection, there appeared a movement in Western art toward accurate representation of the human form. Prime among the exponents of this new school of naturalism in art were Leonardo da Vinci, Michelangelo Buanorroti, Albrecht Durer, Andrea Mantegna, and Andrea Verrocchio. Such was their obsession for scrupulous anatomical accuracy in their artistic depictions that they took to performing elaborate dissections (often in collaboration with eminent anatomists of the day) to enhance their understanding of the structure of the human body.

Availability and procurement of cadavers

Until the eighteenth century, the only lawful source of cadavers for dissection was the gallows. In Italy, papal consent was necessary before the corpse of an executed criminal could be dissected. In Scotland and in England royal assent was required in order to dissect the bodies of hanged felons. These legitimate dissections were intended as nominated public events and were conducted in large halls or amphitheatres. From the early eighteenth century onwards, anatomical theatres, specifically designed for dissection, were built in many of the major centres of anatomical study in Europe, including Leyden, Dublin, Edinburgh, London, Paris, and Louvain. These theatres were the forerunners of the modern-day dissection halls in medical schools. Towards the end of the eighteenth century, France repealed the law allowing dissection of executed criminals. Other European nations, including Britain, soon followed.

Thereafter only unclaimed bodies of persons dying in civil hospitals, prisons, and poor-houses could legitimately be used for dissection. However, the limited availability of legally-obtainable cadavers during the early days of dissection led to the unsavoury practice of ‘grave-robbing’ or ‘body snatching’ — the illegal exhumation and theft of freshly interred bodies for dissection. The scandal of ‘Burke and Hare’ who committed murder to supply corpses to anatomists, led to the very first act of legislation regulating the acquisition and use of cadavers for dissection in Great Britain, the Anatomy Act of 1832. In the present day, laws in different countries ensure that only such bodies as are legally bequeathed to medical institutions are used for dissection.

Preservation of cadavers

From the very earliest days of human dissection until relatively recently, a problem for anatomists was that there was no satisfactory method of preserving cadavers that would allow dissection to be carried out in an unhurried manner. The natural decomposition of the body, a rapid process, dictated the need for the dissection to be accomplished quickly and efficiently (in a matter of 3-4 days at most) before the unbearable stench of the putrefying cadaver made it impossible for the dissector to continue his task. In conditions of excessive humidity and warmth the problem was worse still, for which reason anatomists preferred to perform dissections during the winter months.

Robert Boyle's observation in the 1650s that decomposition of animal and human tissues could be prevented by immersing them in spirits of wine was a notable advance. This remained the principal method of cadaveric preservation until the latter half of the nineteenth century, when the antiseptic and preservative properties of formaldehyde were discovered. In the present day, preservation of cadavers (embalming) is usually accomplished by inserting tubes into a large artery and vein (usually the femoral artery and vein), washing out the blood, and then infusing a mixture of formalin (a 40% solution of formaldehyde), industrial alcohol, phenol, and glycerin. This mixture ensures that the body is both sterilized and preserved, and the glycerin prevents the tissues from becoming excessively hardened, thereby facilitating the process of dissection. As a result of these preservation techniques, there are several museums of human anatomy today containing permanent displays of beautifully dissected specimens. Among the finest and most comprehensive of these is the Wellcome museum of anatomy at the Royal College of Surgeons of England in London.

The study of human anatomy by dissection remains, today, an integral part of the basic undergraduate curriculum in medical schools the world over. A relatively recent innovation is the establishment of centres where experienced surgeons can revise and refine their anatomical knowledge of a particular surgical operation by cadaveric dissection, using precision instruments for incising tissues, operating microscopes for better visualization of structures, high-power drills for cutting bone, and endoscopes for viewing internal anatomy.

— Vishi Mahadevan

See also anatomy; body snatches; Burke and Hare.

noun

The separation of a whole into its parts for study: analysis, anatomy, breakdown. See assemble/disassemble, investigate.

Definition: cutting up
Antonyms: connection, joining, mending, sewing

The cutting down of valleys by river erosion. Thus, a dissected plateau is a level surface which has been deeply cut into by rivers, leaving a close network of valleys with hills in between.

1. the act of dissecting.
2. a part or whole of an organism prepared by dissecting.
3. passage of blood between layers of the wall of a blood vessel.

• blunt d. — separation of tissues along natural lines of cleavage, by means of a blunt instrument or finger.
• sharp d. — separation of tissues by means of the sharp edge of a knife or scalpel, or with scissors.
• water beam d. — the use of a high-pressure jet of saline to remove parenchymal cells, retaining more resistant structures such as ducts, capsule and vessels.

This article is about the biological process. For other uses, see Dissection (disambiguation).

Dissection of a human cheek from Gray's Anatomy (1918).

Dissection (also called anatomization) is usually the process of disassembling and observing something to determine its internal structure and as an aid to discerning the functions and relationships of its components. It may refer also to some spontaneous natural process of disassembly as in aortic dissection.

Contents 1 In biology 2 History 3 Tools used 4 See also 5 References 6 External links

In biology

Dissection is usually applied to the examination of plants and animals. The term is also used in relation to mechanisms, computer programs, written materials, etc., as a synonym for terms such as reverse engineering or literary deconstruction. Dissection is usually performed by students in courses of biology, botany and anatomy and in association with medical and arts studies.

Vivisection refers to the dissection of a living animal, often for the purposes of physiological investigation and always under heavy sedation. However, the term is no longer widely used, in part because more sophisticated techniques have superseded it for many applications. The term is now almost entirely used in a pejorative sense by those who oppose animal testing of any sort.

Dissection is often performed as a part of determining a cause of death in autopsy (on humans) and necropsy (on animals) and is an intrinsic part of forensic medicine, such as would be practiced by a coroner.

History

Early systematic human dissections were carried out by the Greek physicians Herophilus of Chalcedon and Erasistratus of Chios in the early part of the third century BC.^[1] Before and after this time investigators appeared to largely limit themselves to non-human animals.^[2] Roman law forbade dissection and autopsy of the human body,^[3] so physicians such as Galen were unable to work on cadavers. Galen for example dissected the Barbary Macaque and other primates, assuming their anatomy was basically the same as that of humans.^[4][5][6]

Human dissections were also conducted by the Arabian physician Ibn Zuhr (Avenzoar) (1091-1161) in al-Andalus,^[7] followed by several other Arabian physicians: Saladin's physician Ibn Jumay in the 12th century, Abd-el-latif in Egypt circa 1200,^[8] and Ibn al-Nafis in Syria circa 1242.^[9][10]

Unlike pagan Rome, Christian Europe did not exercise a universal prohibition of the dissection and autopsy of the human body and such examinations were carried out regularly from at least the 13th century.^[11][12][13] It has even been suggested that the Christian theology contributed significantly to the revival of human dissection and autopsy by providing a new socio-religious and cultural context in which the human cadaver was no longer seen as sacrosanct.^[14]

Throughout history, the dissection of human cadavers for medical education has experienced various cycles of legalization and proscription in different countries. An edict of the 1163 Council of Tours, and an early 14th century decree of Pope Boniface VIII have mistakenly been identified as prohibiting dissection and autopsy^[15][16], but no universal prohibition of dissection or autopsy was exercised during the Middle Ages. Rather, the era witnessed the revival of an interest in medical studies, and a renewal in human dissection and autopsy.^[17] Some European countries began legalizing the dissection of executed criminals for educational purposes in the late 13th and early 14th centuries, and Mondino de Liuzzi carried out the first recorded public dissection around 1315. Vesalius in the 16th century carried out numerous dissections in the process of performing some of the most extensive anatomical investigations up to his time, but was attacked frequently by other physicians for his disagreement with Galen's studies of human anatomy. For many years it was assumed that Vesalius's pilgrimage to Palestine was an escape from pressures of the Inquisition brought as a result of his work with cadavers. Today this is generally considered to be without foundation (see C.D. O'Malley Andreas Vesalius' Pilgrimage, Isis 45:2, 1954) and is dismissed by modern biographers.

In England, dissection remained entirely prohibited until the 16th century, when a series of royal edicts gave specific groups of physicians and surgeons some limited rights to dissect cadavers. The permission was quite limited: by the mid 18th century, the Royal College of Physicians and Company of Barber-Surgeons were the only two groups permitted to carry out dissections, and had an annual quota of ten cadavers between them. As a result of pressure from anatomists, especially in the rapidly growing medical schools, the Murder Act 1752 allowed the bodies of executed murderers to be dissected for anatomical research and education. By the 19th century this supply of cadavers proved insufficient, however, due to both the continuing expansion of medical schools, and the creation of a number of private medical schools, which lacked legal access to cadavers. A thriving black market arose in cadavers and body parts, leading to the creation of an entire profession of body-snatcher, and even more extremely, the infamous 1827 and 1828 Burke and Hare murders, in which 17 people were murdered in order to sell their cadavers to anatomists. The resulting public outcry largely led to the passage of the Anatomy Act 1832, which greatly increased the legal supply of cadavers for dissection. (See also: History of anatomy in the 19th century.)^[18]

By the 21st century, the availability of interactive computer programs and changing public sentiment led to renewed debate on the use of cadavers in medical education. The Peninsula College of Medicine and Dentistry in the UK, founded in 2000, became the first modern medical school to carry out its anatomy education without dissection, though most medical schools continue to see experience with actual cadavers as preferable to entirely computer-based education.^[19]

Dissections of non-human animals have also been used for educational purposes, often in general science education where the use of human cadavers would not be justified. In the U.S., dissection of frogs became common in college biology classes from the 1920s, and gradually began to be introduced at earlier stages of education. By 1988, an estimated 75–80% of American high school biology students were participating in a frog dissection, with a trend towards introduction in elementary schools. The dissected frogs are most commonly from the Rana genus. Other popular animals for high-school dissection at the time of that survey were, among vertebrates, fetal pigs, perch, and cats; and among invertebrates, earthworms, grasshoppers, crayfish, and starfish.^[20]

Controversy over dissection in U.S. high schools became prominent in 1987, when a California student, Jenifer Graham, sued to require her school to let her complete an alternate project. The court ruled that mandatory dissections were permissible, but that Graham could ask to dissect a frog that had died of natural causes rather than one that was killed for the purposes of dissection; the practical impossibility of procuring a frog that had died of natural causes in effect let Graham opt out of the required dissection. The suit also gave considerable publicity to anti-dissection advocates: Graham appeared in a 1988 Apple Computer commercial promoting its "Operation Frog" virtual-dissection software, and the state of California the same year passed a Student's Rights Bill requiring that objecting students be allowed to complete alternative projects.^[21] The trend towards students opting out of dissection increased through the 1990s.^[22]

Tools used

The following are tools commonly used in biological dissection.

• Scalpel
• Scissors
• Thumb Forceps or Fine point splinter
• Mall probe and seeker
• Surgical Spatula
• Magnifying glass
• Chain & Hooks (surgical)
• Razor
• Blow Pipe (surgical)
• Prong (surgical)
• Teasing needles
• Pipette or Medicine dropper
• Ruler or caliper
• T pins
• Dissecting Pan

See also

• See-through frog

References

1. ^ The discovery of the body: human dissection and it...[Yale J Biol Med. 1992 May-Jun] - PubMed Result
2. ^ P Prioreschi, Determinants of the revival of dissection of the human body in the Middle Ages', Medical Hypotheses (2001) 56(2), 229–234)
3. ^ 'Tragically, the prohibition of human dissection by Rome in 150 BC arrested this progress and few of their findings survived', Arthur Aufderheide, 'The Scientific Study of Mummies' (2003), page 5
4. ^ Vivian Nutton, 'The Unknown Galen', (2002), page 89
5. ^ Heinrich Von Staden, 'Herophilus' (1989), page 140
6. ^ Philip Lutgendorf, 'Hanuman's Tale: The Messages of a Divine Monkey‎' (2007), page 348
7. ^ Islamic medicine, Hutchinson Encyclopedia.
8. ^ Emilie Savage-Smith (1996), "Medicine", in Roshdi Rashed, ed., Encyclopedia of the History of Arabic Science, Vol. 3, p. 903-962 [951-952]. Routledge, London and New York.
9. ^ S. A. Al-Dabbagh (1978). "Ibn Al-Nafis and the pulmonary circulation", The Lancet 1, p. 1148.
10. ^ Chairman's Reflections (2004), "Traditional Medicine Among Gulf Arabs, Part II: Blood-letting", Heart Views 5 (2), p. 74-85 [80]
11. ^ P Prioreschi, Determinants of the revival of dissection of the human body in the Middle Ages', Medical Hypotheses (2001) 56(2), 229–234)
12. ^ 'In the 13th century, the realisation that human anatomy could only be taught by dissection of the human body resulted in its legalisation in several European countries between 1283 and 1365', Philip Cheung 'Public Trust in Medical Research?.', (2007), page 36
13. ^ 'Indeed, very early in the thirteenth century, a religious official, namely, Pope Innocent III (1198-1216), ordered the postmortem autopsy of a person whose death was suspicious', Toby Huff, 'The Rise Of Modern Science' (2003), page 195
14. ^ P Prioreschi, Determinants of the revival of dissection of the human body in the Middle Ages', Medical Hypotheses (2001) 56(2), 229–234)
15. ^ 'While during this period the Church did not forbid human dissections in general, certain edicts were directed at specific practices. These included the Ecclesia Abhorret a Sanguine in 1163 by the Council of Tours and Pope Boniface VIII's command to terminate the practice of dismemberment of slain crusaders' bodies and boiling the parts to enable defleshing for return of their bones. Such proclamations were commonly misunderstood as a ban on all dissection of either living persons or cadavers (Rogers & Waldron, 1986), and progress in anatomical knowledge by human dissection did not thrive in that intellectual climate', Arthur Aufderheide, 'The Scientific Study of Mummies' (2003), page 5
16. ^ 'It must be noted, however, that the pope did not forbid anatomical dissections but only the dissections performed with the purpose of preserving the bodies for distant burial', P Prioreschi, Determinants of the revival of dissection of the human body in the Middle Ages', Medical Hypotheses (2001) 56(2), 229–234)
17. ^ 'Current scholarship reveals that Europeans had considerable knowledge of human anatomy, not just that based on Galen and his animal dissections. For the Europeans had performed significant numbers of human dissections, especially postmortem autopsies during this era', 'Many of the autopsies were conducted to determine whether or not the deceased had died of natural causes or whether there had been foul play, poisoning, or physical assault. Indeed, very early in the thirteenth century, a religious official, namely, Pope Innocent III (1198-1216), ordered the postmortem autopsy of a person whose death was suspicious', Toby Huff, 'The Rise Of Modern Science' (2003), page 195
18. ^ Cheung, pp. 37–44
19. ^ Cheung, pp. 33, 35
20. ^ F. Barbara Orlans, Tom L. Beauchamp, Rebecca Dresser, David B. Morton, and John P. Gluck (1998). The Human Use of Animals. Oxford University Press. pp. 213. ISBN 0195119088. 
21. ^ Orlans et al., pp. 209–211
22. ^ "Frogs' Best Friends: Students Who Won't Dissect Them". The New York Times. May 29, 1997. http://query.nytimes.com/gst/fullpage.html?res=9D00E5DF123AF93AA15756C0A961958260. 

External links

Wikimedia Commons has media related to: Dissection

• How to dissect a frog
• Dissection Alternatives
• Human Dissections
• Virtual Frog Dissection
• Alternatives To Animal Dissection in School Science Classes
• Research Project on Death and Dead Bodies, last conference: "Death and Dissection" July 2009, Berlin, Germany

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